Doorknob assembly



FIG. 1 is a perspective view, taken from the front, top, and right side, of a doorknob assembly, in accordance with my new design;

FIG. 2 is a front elevational view of the doorknob assembly shown in FIG. 1;

FIG. 3 is a left side elevational view of the doorknob assembly shown in FIG. 1;

FIG. 4 is a right side elevational view of the doorknob assembly shown in FIG. 1;

FIG. 5 is a top plan view of the doorknob assembly shown in FIG. 1, the bottom plan view being identical thereto; and,

FIG. 6 is a rear elevational view of the doorknob assembly shown in FIG. 1.

The broken lines illustrate environmental structure which forms no part of the claimed design. 

CLAIM The ornamental design for a doorknob assembly, as shown and described. 